Alcohol-impaired driving is a significant problem in the United States. The proposed research seeks to expand our understanding of the factors leading people to drive while impaired by testing the acute effects of alcohol in a group characterized by increased risk for alcohol-intoxicated driving (i.e., adults with ADHD). The project will examine alcohol responses in this group with a focus on how atypical alcohol responses may place this group at heightened risk to drive after drinking. First, the proposed research will examine how alcohol interacts with environmental factors to impair driving ability in adults with ADHD. Previous research has shown that the effects of alcohol are more pronounced in certain environmental circumstances, such as the presence of visual distraction or motivational conflict. These findings are important because such environmental circumstances are quite common outside of the laboratory, so they may explain why some drivers show appreciable impairment even at blood alcohol concentrations (BACs) below the legal limit of intoxication (i.e., 80mg/100ml). The proposed research will examine the interaction of alcohol intoxication and environmental factors in a group of high-risk drinkers (i.e., adults wih ADHD) under several doses of alcohol. This will test whether high-risk environmental circumstances cause adults with ADHD to show heightened behavioral impairment under alcohol, even at BACs below the legal limit of intoxication. Second, the proposed project will examine whether adults with ADHD overestimate their ability to drive after consuming alcohol. Previous research has shown that subjective evaluation of impairment informs people's decisions to drive after drinking. It is also well known that individuals with ADHD show impaired self-evaluation processes, so they may underestimate the degree to which alcohol impairs their driving ability (Knouse et al., 2005; Weafer et al., 2008). Further, they may not perceive how driving in high-risk scenarios exacerbates their level of behavioral impairment. These specific aims will be achieved by examining the interactive effects of alcohol and environmental factors on objective and perceived driving ability in adults with and without ADHD.